A ventilation or heating/cooling element and a ventilation or heating/cooling clothing item

ABSTRACT

A ventilating or heating/cooling element having a first side having an air permeability of 15-800 m 3 /m 2 /h at 120 Pa. The first side is for directing an air flow toward a person. The ventilating/cooling/heating element may form or form part of a mattress, a duvet/blanket, a pillow, a sleeping bag, a seat, a clothes item or the like. A pump may be provided for providing air into the ventilating/cooling/heating element, or one or more openings may be provided for receiving air when a person is moving, such as when riding a motor cycle.

The present invention relates to a ventilation or heating/cooling element primarily for use in heating, cooling and/or ventilating a person. A primary objective is to cool a person in hot environments such as when sleeping. Naturally, heating a person in cold environments is also an objective. Mattresses, duvets, pillows and clothing with air supply have been proposed for many years, but have not been accepted. One reason may be the noise generated by the rather large air flows. Another reason may be that the large air flows contemplated in fact is not comfortable.

Solutions of ventilation of e.g. mattresses may be seen in: GB889865, U.S. Pat. No. 7,945,979, U.S. Pat. No. 6,446,290, U.S. Pat. No. 6,581,225, U.S. Pat. No. 4,665,575, EP0493267, U.S. Pat. No. 3,529,310, WO11091788, CA2623097, US2009271923, WO11093762, US2009276958, FR2754156, U.S. Pat. No. 5,165,127, U.S. Pat. No. 6,085,369, U.S. Pat. No. 6,263,530, EP1951089, US2011035880, AU2008200388, U.S. Pat. No. 6,546,576, GB1386249, EP1762211, U.S. Pat. No. 7,913,332, DE20313150 U1, U.S. Pat. No. 5,730,120, WO08123640, US2003150060, GB1168251, U.S. Pat. No. 7,666,214, EP1804616, GB1311461, U.S. Pat. No. 7,165,281, EP0957727, U.S. Pat. No. 6,855,158, U.S. Pat. No. 5,392,847, EP0859564, EP1723877, GB2414178, U.S. Pat. No. 6,487,739, U.S. Pat. No. 6,687,937, U.S. Pat. No. 6,402,775, U.S. Pat. No. 6,764,502, U.S. Pat. No. 4,884,304, U.S. Pat. No. 5,033,136, U.S. Pat. No. 6,551,347, U.S. Pat. No. 7,001,417, U.S. Pat. No. 7,908,687, U.S. Pat. No. 7,631,377, U.S. Pat. No. 7,975,331, GB2446572, U.S. Pat. No. 3,101,488, US2011035879, U.S. Pat. No. 8,074,307, GB965133, GB724910, US2006101577, U.S. Pat. No. 8,065,763, U.S. Pat. No. 3,230,556, EP1947986, U.S. Pat. No. 6,269,504, U.S. Pat. No. 6,701,556, U.S. Pat. No. 7,191,480, U.S. Pat. No. 7,191,482, U.S. Pat. No. 7,480,953, U.S. Pat. No. 7,617,555, U.S. Pat. No. 7,966,680, DE6927743 U, U.S. Pat. No. 5,109,560, GB2333230, DE202010017223 U1, WO02062185, U.S. Pat. No. 4,959,877, U.S. Pat. No. 7,181,786, US2007169264, CA2541341, US2012017371, US2004031103, GB2456814, US2005086739, GB2398506, U.S. Pat. No. 3,266,064, U.S. Pat. No. 7,877,827, U.S. Pat. No. 7,996,936, US2011296611, U.S. Pat. No. 6,363,551, U.S. Pat. No. 7,240,386, U.S. Pat. No. 7,467,435, U.S. Pat. No. 7,650,658, U.S. Pat. No. 7,950,084, U.S. Pat. No. 7,272,936, U.S. Pat. No. 7,480,950, U.S. Pat. No. 7,937,789, U.S. Pat. No. 7,914,611, U.S. Pat. No. 8,118,920, EP1044637, WO12019236, U.S. Pat. No. 4,939,804, GB1321865, US2008263776, US2010043143, WO9510211, DE102009044308, EP0113149, US2012000207, US2011314837, US2011289684, US2011041246, US2008028536, U.S. Pat. No. 4,777,802, WO9633642, U.S. Pat. No. 6,336,237, DE10139484 B4, U.S. Pat. No. 6,730,115, U.S. Pat. No. 6,826,792, CN85100943, CN2090655, CN2239194, CA1272815, CN2068786, TWM392597, CN2571272, DE202005011452 U1, US2007033733, JP3186632 B2, JP7313306 A2, KR20020083648, CN2882417, CN201139285, US2009145936, JP3814987, WO2011150427, U.S. Pat. No. 6,273,810, US2013036549 and US2012024154.

In some high-end car brands, such as Mercedes Benz, seats are available which have air permeable seats through which air may be forced to increase the comfort of the driver.

It has been found that, though, a quite low air flow is required to provide the desired cooling/ventilation, so that a very comfortable situation is obtained. This may be obtained using a rather dense material or a material with a rather low air permeability.

A first aspect of the invention relates to an inflatable ventilation, heating and/or cooling element comprising a first side, a second side and an air inlet, the first side having an air permeability of 15-800 m³/m²/h at 120 Pa. The air permeability of the first side may be desired to be 15-500, such as 15-100 or 20-400, such as 25-300, such as 30-100, such as 35-70, such as 40-65 m³/m²/h at 120 Pa. This air permeability may also or alternatively be selected within the interval of 20-200, or 15-600, such as 20-300, or 20-500, such as 30-300, such as 30-100, or 30-600, such as 50-200 m³/m²/h at 120 Pa.

Preferably, the first and second sides are the main or major sides of a generally flat element or an element with a thickness being less than 0.2 times a largest dimension of the first side. Naturally, the element may have additional sides, such as an edge portion bridging between the first and second sides. The air inlet(s) may be provided at any position, such as in the edge portion.

As the air permeability usually is generated by localized openings, such as openings in a weave, or at least is often non-uniform over the surface, the air permeability of the first side preferably is a mean air permeability. As will be described below, it may be desired to provide different areas of the first side with different (mean) air permeability.

Usually, an air pressure in the element during use is lower than 120 Pa, such as lower than 100 Pa, such as lower than 80 Pa, such as lower than 70 Pa, such as lower than 50 Pa, such as lower than 30 Pa, such as lower than 20 Pa, such as lower than 10 Pa. The air pressure may be in the range of 0-100 Pa, such as 5-50 Pa.

The first and second sides preferably are first and second separate layers between which a cavity is provided for receiving air from the inlet(s).

The inlet may be provided with a one-way valve if desired and/or may be provided with a connector for attachment to a hose/tube or the like.

In one situation, the second side is at least substantially air impermeable. Then, also other parts, such as the above-mentioned edge portion may also be air impermeable. In general, “air impermeability” preferably will be an air permeability lower than 15, such as 10, 5 or less m³/m²/h at 120 Pa.

When only the first side has an air permeability air is only fed from the inlet(s) through the first side. Thus, no air is lost via the other side(s) and/or no power is lost forcing air through such other sides.

In some embodiments, it is desired to have different air permeability of different areas of the first side. It thus may be desired to provide, in the first side, one or more first areas and one or more second areas, the first and second areas not overlapping, where the first area(s) have a larger air permeability than the second area(s). The air permeability of each first side being a mean permeability of the area defined thereby.

In general, an air permeable surface or layer may be obtained in a number of manners. Presently preferred manners are weaves or non-woven materials. Also solid materials having holes or channels formed therein may be used.

Interesting materials may be any type of polymer, such as polyester. Also cotton or a mixture of cotton and a polymer may be used. Rubber and other natural or synthetic materials may be used alone or used in a combination with e.g. a polymer. The permeability of the material may be generated in different manners. In one manner, the surface/layer is weaved or non-woven where the inherently porous or open structure thereof, such as by controlling a thickness/density thereof and/or the weaving thereof. Alternatively or additionally, openings, channels and/or holes may be provided in the surface/layer so as to generate permeability. The density (channels/holes/openings per unit of area) may be altered as may a dimension, such as a diameter or cross section or mean cross section or lowest cross section (in a plane parallel to the surface/layer) of each channel/opening/hole or the channels/openings/holes.

Combinations may be used, such as wherein the first and second areas comprise a woven or nonwoven material and wherein the first areas further comprise one or more openings or channels through the material. Thus, the second areas have the lower air permeability and the first areas a higher permeability due to the combination of the effect of the weave/non-woven and the channels/openings.

The size and number of openings may be adapted to achieve the desired permeability. Openings may be 0.01-1.5 mm, such as 0.05-1 mm, such as 0.1-0.6 mm in diameter, for example.

In one embodiment, the lower air permeability may be 15-100, such as 20-70, such as 30-50 m³/m²/h at 120 Pa and the higher air permeability may be 30-150, such as 40-100, such as 50-75 m³/m²/h at 120 Pa.

The first and second areas may form all of the first surface, and the first areas may cover 10-80%, such as 40-70% of the area of the first surface.

In one embodiment, the element further comprises a pump for providing air to the air inlet. Naturally, sensors and the like may be provided for sensing a flow, air pressure, temperature, humidity and the like of the air outside or in the element or pump. Also, or alternatively, elements may be provided for controlling such parameters, such as a heater, a cooler, a humidifier, a de-humidifier, or the like.

When providing air between the first and second sides, it is desired to maintain a relatively flat shape of the element. A balloon shape is usually not desired. In such situations, it is preferred that the ventilating/cooling/heating element comprises one or more limiting elements defining a maximum distance between a part of the first side and the second side. Preferably, such limiting elements will ensure that when the second side is plane, such as when resting on a plane surface, all parts of the first surface will extend within a threshold distance from the same plane surface. Such thickness limiting elements may be flexible, such as threads or stitches extending between the first and second sides, points or areas where the first and second sides are fixed to each other, or more rigid, such as a foam or another air permeable sheet-like material to which the first and second sides are attached. This attachment may be over the full first/second surface or within areas or lines thereof (such as along lines in a predetermined, such as chequered, pattern or other patterns as are seen in e.g. quilted products.

In a preferred embodiment, the ventilating/cooling/heating element is intended for use in supporting a person, such as when used in or as a mattress or seat. In this situation, all of or a part of the person's weight will be exerted on the element. In order to not block the air flow in the element, the element in such situations preferably comprises a spacer element provided between the first and second sides, the spacer element being configured to allow air flow there through during a force exertion thereto. This force exertion may be when exerting the force of gravity acting on 2kg or more over an area of 10 cm×10 cm on the first surface in a direction toward the second surface.

Spacer materials of this type may be certain types of foams, usually open foams, but also material such as the 3 mesh spacer fabric from Müller textil BmbH (http://www.mullertextiles.com/index.php?id=70) or the 3D spacer fabric from Culzean textile solutions (http://www.culzeamcom/spacer-fabric.asp). These materials provide a spacer material by having a large number of fibres distributed over the area thereof and extending between a lower and upper surface, where the many fibres, to compress the spacer material, need to be bent. The number of fibres is so high that total compression requires a large force, whereby the spacer material usually will allow air penetration there through at least for most parts.

In one first situation, the ventilating/cooling/heating element forms a mattress or a part of a mattress, where the first side is directed upwardly. The ventilating/cooling/heating element may form an upper surface or part of the mattress, where other parts of the mattress are usual parts, such as legs, springs or the like. The ventilating/cooling/heating element may form only a part of the mattress and be operational to provide the air/ventilation/cooling/heating so that a remainder of the mattress may provide the softness of the mattress. Alternatively, the spacer element of the present ventilating/cooling/heating element may be configured to provide the desired softness of the mattress.

The mattress may comprise springs, foam or the like for providing the softness. These springs or this foam may form the spacer element. The mattress may additionally or alternatively be an air mattress where a high air pressure in the mattress generates the softness. In that situation, a pump may be desired for maintaining the air pressure in spite of the air permeability of at least the first surface.

In another situation, the ventilating/cooling/heating element may form a pillow or a part thereof, where the first side is directed away from a central portion, such as a stuffing, of the pillow. Thus, the first side is directed toward, or may directly form, a pillow surface on which the person's head may rest while being cooled/ventilated. The central portion may be configured to provide the pillow with softness and volume and may be provided with a stuffing. Alternatively, an air pressure may expand the pillow.

In yet another situation, the ventilating/cooling/heating element forms part of a seat or chair, such as for a vehicle, where the first side is directed away from a central portion of the seat/chair and toward a position of a sitting person. As mentioned above, air permeable vehicle seats with forced air feeding are known with, however, quite large air permeability.

For both the pillow and the seat, the above spacer comments are also relevant.

In another type of embodiment, the element forms or forms a part of a duvet or blanket, the first side directed away from a central portion of the duvet/blanket. Also in this situation, a spacer element may be desired, if the duvet or blanket is rather heavy and thus may, due to its weight, block air flow in the cooling/heating/ventilating element, when the element is positioned between the heavy parts and the person. Alternatively, the duvet/blanket may be formed by the cooling/heating/ventilating element, or any remaining parts of the duvet/blanket may be rather light so as to not block air flow therein. The first side preferably is directed downwardly toward the sleeping person. The duvet/blanket thus may have a side configured for being directed toward the person and another side which is not. Alternatively, the duvet/blanket may have two opposite sides both having an air permeability either using two cooling/heating/ventilating elements or by having the duvet/blanket formed by a single cooling/heating/ventilating element with also the second side air permeable. Any elements, such as a stuffing, desired for insulating the duvet/blanket may be provided outside of or inside the cooling/heating/ventilating element.

Yet another embodiment relates to the ventilating/cooling/heating element forming or forming a part of a sleeping bag comprising a sleeping cavity, the first side directed toward the sleeping compartment. The same considerations as those of the duvet/blanket apply here.

A second aspect of the invention relates to a clothing item adapted to be worn by a person, the clothing item having a ventilating/cooling/heating element, such as that of the first aspect, having an inner surface and an outer surface defining there between a volume into which one or more air inlets may guide air, the inner surface having an air permeability of 15-800 m³/m²/h at 120 Pa.

This clothing item may be a shirt, trousers, a vest, a jacket, a gown, a dress, a t-shirt, a pull-over or the like. The inner surface is that directed toward the person wearing the clothing item and the outer surface toward the surroundings of the person. Naturally, the clothing item may comprise a cavity wherein the ventilating/cooling/heating element is provided, so that the element is not visible from outside the clothing item. In that situation, the clothing item may have an innermost layer with an air permeability higher than that of the first surface.

Clothing items of this type may be desired in hot surroundings where cooling is desired. Alternatively, the items may be used in cold surroundings for heating the person. The present ventilating/cooling/heating element may form all of the clothing item, or the clothing item may comprise additional elements or parts, such as buttons, zippers, pockets or the like. Some parts, however, of the clothing items may not need to be or be desired to be ventilated, such as legs or arm portions, so that the clothing item usually will comprise additional elements or parts than the ventilation/cooling/heating element. Additionally, collars, shoulder pads and the like may be provided if desired.

It may be desired that the outer surface is at least substantially air impermeable. This may be in order to better control the flow of air in the ventilating/cooling/heating element or in order to not waste air or energy by air flowing out of the outer surface. This desire may also stem from other requirements of the clothing item, such as when using the clothing item. Often, jackets are desired relatively air impermeable. Also water impermeability may be a desire.

All the above considerations relating to the first aspect of the invention are equally applicable in relation to the clothing item. Thus, different zones with different air permeability may be provided as may a pump and the like.

In one situation, the cooling/heating/ventilating element may be in the form of a clothing item to be worn under other clothes, such as under a jacket. Thus, the ventilating/cooling/heating element may be worn when desired, such as when wearing the jacket under hot circumstances. In one situation, the jacket is a motorcycle jacket which will become uncomfortable to wear in hot weather. However, wearing it is a safety desire of the driver. The cooling/heating/ventilating element may be worn under the jacket such as attached to the jacket as a type of lining.

In an interesting embodiment, an air inlet comprises an opening through the outer surface and is positioned on a front of the clothing item when worn by a person. Then, air may be forced into the opening by the person wearing the clothing item simply moving forward. This is e.g. the situation when the person is jogging, skiing, paragliding, jumping in a parachute, or riding a horse/bike/moped/scooter/motorbike.

Naturally, elements may be provided for preventing this air entering the ventilating/cooling/heating element from cooling the person locally at the entrance. Thus, air guides may be provided for guiding this air, inside the element, away from the entrance and to other parts of the ventilating/cooling/heating element.

In another situation, the clothing element may further comprise an air pump configured to provide air through the inlet(s).

A final aspect relates to a method of operating or using an element or an item according to any of the above aspects, wherein air is fed to between the inner/first surface and the second/outer surface. This may be facilitated using e.g. a pump as described above, and the amount of air or the pressure thereof, or the pressure of air between the first/inner surface and the second/outer surface may be adapted to obtain the above pressure difference over the first/inner surface and/or flow (per surface and per time) described above.

Clearly, as is described above, the comfort achieved with the rather low flow or permeability is higher, as no draught is felt but merely a comfortable removal of heat/humidity, for example.

Thus, any of the above embodiments and examples may be used in this method to achieve the above-mentioned effect on or for a person or body provided on/below/between the first surface or inner surface.

In the following, preferred embodiments of the invention are described with reference to the drawing, wherein:

FIG. 1 illustrates a first embodiment of the invention in the form of a mattress,

FIG. 2 illustrates a second embodiment of the invention in the form of a pillow,

FIG. 3 illustrates a third embodiment of the invention in the form of a duvet,

FIG. 4 illustrates a fourth embodiment of the invention in the form of a sleeping bag,

FIGS. 5 and 6 illustrate a fifth embodiment of the invention in the form of a vest,

FIG. 7 illustrates the air intake of the embodiment of FIGS. 5 and 6,

FIG. 8 illustrates different manners of obtaining a gas permeable surface and

FIG. 9 illustrates the use of a spacer material within the embodiments.

In FIG. 1, a mattress 10 is illustrated having an upper side 12 and a lower side 14 as well as a rim portion 16 wherein an opening 18 is provided.

The upper side 12 is gas permeable whereas the lower side 14 and the rim portion 16 are at least substantially gas impermeable.

When providing air/gas into the mattress 10 through the opening 18, such as using a pump 15 and a hose 17, the mattress 10 will experience a higher gas pressure, and gas will exit the mattress 10 through the gas permeable surface 12.

Mattresses 10 with gas permeable upper sides are known in the art, but the present mattress 10 is novel in that the gas permeability of the upper surface 12 is rather low.

In this manner, it is ensured that the amount of gas actually exiting the surface 12 is sufficiently low to not cool the person lying on the mattress 10 too much. It has been found that the gas permeability or air permeability of the upper layer 12 actually should be rather low.

Presently, the air permeability of the upper surface 12 preferably is in the interval 50-750 m³/(hour*m²).

In FIG. 1, a standard mattress is illustrated in hatched lines, where the mattress 10 is provided on top of the mattress. Alternatively, all of the mattress illustrated may be formed by the ventilating/cooling/heating mattress 10 now also comprising other elements for generating the softness of the mattress.

Naturally, the present technology may be used also for a number of other purposes, such as a pillow 20 as is illustrated in FIG. 2, a duvet 30 illustrated in FIG. 3, and a sleeping bag 40 illustrated in FIG. 4, where the upper/inner side 12 again is air permeable and the lower side 14 and any sides 16 are at least substantially air impermeable.

FIG. 5 illustrates a very different embodiment of the invention, a vest 50 having an inner, gas permeable side 12 and an outer, at least substantially air impermeable side 14. The vest may itself be formed by a ventilating/cooling/heating element or such an element may be formed or provided within the vest—either between layers of fabric of the vest or on the inside thereof.

The vest may, as is also illustrated in FIG. 1, be provided with a pump or fan 15, but especially when for a person moving though the air, such as a motorcycle driver, a cyclist, a jogger, a moped driver, a person in an open vehicle, a parachute jumper or the like, no other manner may be required to force air into the vest than the force of the air caused by the movement.

In FIG. 5, two different types of air intakes are illustrated. Air intakes 18′ are illustrated on top of the shoulders which receive air and guides the air into distributing channels 13 (see FIG. 6) which guide the air into the vest between the surfaces 12 and 14.

In FIG. 5, another type of air intake 18′ is illustrated which are gas permeable areas 18′ on the chest of the vest, where air may be forced into the space between the layers 12 and 14.

In FIG. 7, the air entrance 18′ is illustrated as is a blocking layer 19 positioned between the air entrance 18′ and the layer 12 so as to prevent over-cooling at the surface 12 at the air entrance 18′ due to the air being forced from the outside directly toward the part of the surface 12 directly at the opening 18′. Also this air intake may be combined with air channels guiding the air to other parts of the vest.

Illustrated in FIG. 7 is also a thread 16′ connecting the first and second layers 12/14 to each other. The function of this thread 16′ is to prevent the vest from assuming a balloon shape when air is forced into the space 16.

The threads 16′ may be provided at any desired positions such as along lines in any desired pattern, such as a chequered pattern illustrated in FIG. 6. In this manner, the layers 12 and 14 form a relatively flat element even when air is forced into the space 16.

In FIG. 8, different manners are illustrated of providing an air permeable layer. A woven material 12′ is illustrated which, naturally, will be air permeable. Also, a surface 12 is illustrated wherein areas 12″ are provided with through-going bores through which air may escape the space between the layers 12/14.

Naturally, combinations of such layers may be preferred, such as when providing all of the surface 12 as a woven surface having an overall air permeability but then increasing the air permeability at predetermined areas, such as at the feet and head of a person lying on the mattress.

Different ventilating/cooling/heating elements may be configured for cooling persons at different positions. A vest, for example, may be configured to cool the back and neck of the person, where a seat may be configured to cool the neck, back and back side of the person.

In FIG. 9, a suitable inner structure of the embodiments illustrated is provided. Between the layers 12 and 14, a spacer material 11 is provided which is more or less un-compressible but, preferably, still bendable, and the function of which is to ensure that air within the space between the surfaces 12 and 14 is able to reach all parts of the surface 12, so that no parts thereof are inactive due to somebody or something blocking the air passage from the opening 18/18′ to this area. This blocking could be a person lying on the mattress 10 and compressing a part thereof or the folding thereof or any of the other embodiments to create a blocking of air passage toward a part of the surface 12.

Depending on the properties of the spacer material 11, it may be preferred to cover this with another, such as a softer or more pliable, material 11′. The presently preferred spacer material may have a tendency of making noises when bent/deformed, which may be undesired. Such noises or such bending/deformation may be reduced by providing a soft layer 11′, such as a foam, between the spacer material 11 and the surface 12. The foam 11′ may be an open foam or a woven/non-woven material or the like allowing air passage from the spacer material 11 to the surface 12 or may be a closed foam in which through-going channels 11″ are provided to allow for such air passage. 

1.-15. (canceled)
 16. An inflatable ventilation or heating/cooling element comprising a first side, a second side and an air inlet, the first side having an air permeability of 15-800 m³/m²/h at 120 Pa.
 17. An element according to claim 16, wherein the second side is at least substantially air impermeable.
 18. An element according to claim 16, wherein, in the first side, one or more first areas and one or more second areas are provided, the first and second areas not overlapping, where the first area(s) have a larger air permeability than the second area(s).
 19. An element according to claim 18, wherein the first and second areas comprise a woven or nonwoven material and wherein the first areas further comprise one or more openings or channels through the material.
 20. An element according to claim 16, further comprising a pump for providing air to the air inlet.
 21. An element according to claim 16, the element comprising one or more element defining a maximum distance between a part of the first side and the second side.
 22. An element according to claim 16, further comprising a spacer element provided between the first and second sides, the spacer element being configured to allow air to flow there through during compression thereof.
 23. An element according to claim 22, forming one or more of: a mattress, where the first side is directed upwardly, a pillow, where the first side is directed away from a central portion of the pillow and/or part of a seat or chair, where the first side is directed away from a central portion of the seat/chair and toward a position of a sitting person.
 24. An element according to claim 16, forming part of a duvet or blanket, the first side directed away from a central portion of the duvet/blanket.
 25. An element according to claim 16, forming part of a sleeping bag comprising a sleeping cavity, the first side directed toward the sleeping compartment.
 26. A clothing item adapted to be worn by a person, the clothing item having a ventilating/cooling/heating element having an inner surface and an outer surface defining there between a volume into which one or more air inlets may guide air, the inner surface having an air permeability of 15-800 m³/m²/h at 120 Pa.
 27. An item according to claim 26, wherein the outer surface is air permeable or at least substantially air impermeable.
 28. An item according to claim 26, wherein an air inlet comprises an opening through the outer surface and is positioned on a front of the clothing item when worn by a person.
 29. An item according to claim 26, further comprising an air pump configured to provide air through the inlet(s).
 30. A method of operating an element or an item according to claim 16, wherein air is fed to between the inner/first surface and the second/outer surface.
 31. A method of operating an element or an item according to claim 26, wherein air is fed to between the inner/first surface and the second/outer surface. 